In some processes, small amounts of oxygen, either free oxygen or oxygenated hydrocarbons, in the feedstream to the process can cause problems in the process unit. Oxygen contamination can create one or more of corrosion problems by forming naphthenic acids, fouling by forming gums with olefinic material, solvent degradation in aromatic extraction units, and degradation of zeolitic adsorbents. Therefore, great care is taken to ensure that the feedstream does not contain oxygen, such as by nitrogen blanketing feed storage tanks, and minimizing potential air leaks into the system. However, hydrocarbon feeds that have been shipped or stored in unblanketed storage may contain oxygen which must be removed.
This oxygen contamination has traditionally been removed in an oxygen stripper. The feed is heated to about 180° C. to strip the free oxygen and to break down the unstable oxygenates, which requires a significant amount of energy and capital. In addition, there can be corrosion problems with the oxygen stripper overhead system due to the oxygen, water, and naphthenic acids, and fouling problems in the lower reboiler tubes due to the presence of the oxygenates and olefins.
There is a need for a method of removing oxygen from hydrocarbon process streams.